1. Field of the Invention
This invention relates to a constant velocity joint.
2. Discussion of the background
Japanese patent application publication No. 58-214019 discloses a constant velocity joint whose outer race has plural outer ball grooves. The outer ball grooves are undercut so that a bottom of each outer ball groove is located at a longer distance from a rotational axis of the outer race at a longitudinally central portion of the outer ball groove than at its opening end. Because the undercut is not easily forged, machined or ground, the manufacturing cost of the outer ball groove increases.
Another conventional constant velocity joint is a so-called undercut free joint whose outer race has plural ball grooves extending parallel to the rotational axis of the outer race from the center portion to the opening side.